Process of producing ferromanganese alloys.



H. SCHAGRINt PROCESS OF PRODUCING FERROMANGANESE ALLOYS.

APPLICATION FILED OCT. 25. I915.

1 ,1 90,679. Patented July 11, 19m.

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HARRY SCHAGRIN, 015 SOUTH BETHLEHEM, PENNSYLVAITIA.

PROCESS OF PRODUCING FERROMANGANESE ALLOYS.

Specification oi Letters Patent.

Patented rlluly 11, 1216.

Continuation of application Serial Ito. 3,785, filed January 22, 1915. This application filed October 25, 191% I Serial No. 57,853.

To all whom it may concern:

Be it known that I, HARRY Sonnemu, a citizen of the United States, residing at South Bethlehem, in the county of Northampton and State of Pennsylvania, have invented certain new and useful Improvements in Processes of Producing Ferromanganese- Alloys; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a process for producing from the waste clinker or cinder, from zinc furnaces, an alloy of iron and manganese containing none or a small quantity of silicon, while at the same time recovering the zinc,'and has for its object'to produce a method of obtaining this product.

in an efiicient and expeditious manner.

To these ends the invention consists in the novel steps constituting my invention, as well as in the novel construction of furnace for carryingout said steps, all as will be. more clearly hereinafter disclosed and particularly pointed out in the claims.

This application is filed as a continuation for my copending application No. 37 85,

- dated January 22, 1915.

til

Referring to the accompanying drawings forming a part of this specification, in which like numerals designate likeparts in all the views, Figure 1 is a diagrammatic sectional view of a furnace suitable for carrying out the process; and Fig. 2 is a sectional View taken'on a Plane at right angles to that on which Fig. 1 is taken.

' Referring to said drawings, 1 indicates any suitable base portion for the furnace, 2 a stack, 3 a conveyer comprising a screw member 4, leading to said stack, 5 a hopper or other suitable means from which the material of the charge 6 may be fed to said screw a and into the said stack 2, all as will be clear from the drawings, and? represents any suitable source of power for operating the screw 4.

It is preferred to use an alternating current as it makes it easier to control the temperature, and when such current is used it is convenient to provide a plurality of stacks 2, 8, 9 and 10 and a plurality of conveyers such as 3, 11, 12 and 13 adapted to feed-ma:

terial to said stacks as indicated, and, told cate between successive pairs of stacks electrodes such as 14, 15 and 16, joined by the wires 17, 18 and 19 to any suitable source of current. The said charge material 6 being fed to said stacks, it readily descends toward the bottom of the furnace as indicated, whereupon a suitable current being passed through said electrodes, the said charge material becomes melted and forms a liquid pool such as 20. The evolved gases may be sucked from the heated charge at a point above said pool by means of the pipes 21 connected to the interiorof the furnace, and joined by the pipe 22 to the suction chamber 23, to which is connected the suc' tion device 24:.

In order that my process may be more clearly understood it is said: The waste clinker, or cinder, from some zinc smelters, especially those employing franklinite, or willemite ores, contain as much as15 per cent. to 22 percent. of manganese oxid MnO, which is mixed with say 28 per cent. to 56 A1 0,, about 10 per cent. calcium oxid,

CaO, about 2 per cent. manganese oxid, Mn(), and about 4 per cent. to 5 per cent. zinc oxid ZnO. I crush this clinker to a suitable size for furnacing, and mix carbon with it up to about 25 per cent. of its weight as well as a suitable quantity of lime stone to act as a fluxing agent. I prefer to use waste coal dust as a source of carbon and it may be combined or held in the charge 6 in any suitable manner. When the charge is thus prepared, 1' feed it to one or more stacks of the furnace as indicated in the drawings, so that it surrounds the bottom ends of the electrodes and current is turned on.

The temperature is observed and the current is allowed to ass until the charge is raised to a point su cient to fuse the same, which may in some cases be as high as 1500 C. or possibly higher. The charge then begins to fuse and to melt, thus forming the molten pool 20 wherein the molten iron and manganese settle down and the slag rises to the top.

During the process of melting or fusing, the zinc contained in the charge'is volatil ized and passes ed with the gases and ante vapors. That is to say, by far the larger portion of the zinc is sucked out of the charge through the pipes 21 and 22 into the chamber 23. But, another portion of said zinc vapors passes up beyond said pipes 21, and condenses on the downcoming charge in the stacks and in the conveyers above the same. That portion of the zinc which thus condenses on the charge 6 is reconveyed back to the fusion zone and is revolatilized, while that portion of the zinc which is sucked out of the furnace through the pipes 21 and 22 is conveyed to the suction chamber 23 along with the other gases where it may be suitably separated out by any preferred means, preferably by means,

of bags or by a gravity process.

I prefer not to admit oxygen or air into the furnace, but to maintain a reducing atmosphere therein at all times, so that the manganese oxid is rapidly reduced, and the metallic manganese volatilized in the fusion zone. I have, however, discovered that this manganese vapor is not carried off to any substantial extent by the evolved carbon monoxid CO, and other gases, although some metallic manganese and also some manganese oxid does pass ofi with the zinc, and this portion of the manganese may be suitably recovered if desired. The evolved gases and vapors that are not sucked into tha chamber 23,

escape up through the stacks such as 9, and conveyers such as 12. I have further discovered that the larger proportion of the reduced manganese is caught in the fusion zone by the molten iron and silicon, where it alloys with the same, and therefore this said larger proportion of manganese is borne down into the molten bath 20 on the hearth of the furnace.

The limestone present, forms a slag whichcarries ofl' practically all the aluminum, and all or substantially all, the silicon, leaving behind only iron and manganese, or iron, manganese and say from zero per cent. to one per cent. of silicon, which forms a ferro-manganese alloy containing from zero per cent. to one per cent. of silicon.

In addition to the manganese that is caught in the fusion zone by the molten metals there present, a considerable quantity passes above said zone in 'a state of vapor and is condensed on the down coming charge material, whereupon it is revolatilized when it reaches the fusion zone and is then caught to a greater or less extent by the fused metals in the manner above disclosed. The result of this action of repeatedly causing the volatilized manganese to return to the fusion zone is to cause a say 20% of-iron and, say, only 10% of manganese, it is evident I can by a suitable control of the temperature readily produce a ferro-manganese alloy containing say 25% to 30% .manganese or even higher if desired. That is to say, in treating this low grade material, I find that the iron oxid is reduced before the manganese oxid, and that when about 1500 C. is reached, the loss of manganese will be excessive unless some precaution is taken to prevent it. On the other hand, the silica is not reduced until after the manganesehas been volatilized and until after'1500. C. has been passed. Accordingly, I so control the temperature by controlling the current as to prevent the upper portions of the chargeand furnace from reaching a temperature sufficiently high to permit the manganese to escape from the furnace, and thus be entirely lost.

I have discovered that if the molten bath is kept at say substantially 1500 C. that 1t will be sufliclently molten to readily absorb all the manganese which is returned to it .by the down coming charge, and yet the temperature of the upper portions of the charge will'not be sufliciently great to permit said manganese to escape. 1n large quantities from the furnace. Accordingly, I have discovered that a high percentage of manganese can be alloyed with the iron in a low grade material if the molten bath in the furnace is not. permitted to rise very much above 1500 C. Again, I have found-that in carrying out this process if the silica is allowed to reach a temperature-of say 1700 C. not only will the .upper portions of the charge be too hot to sa ve a large proportion of the manganese, but the reduced silicon 10o will readily alloy with the molten iron and thus produce a ferro-silicon with a much less percentage of manganese-therein, than would otherwise be the casekina ferro-man- .ganese alloy if. the temperature is kept around 1500 C. In other words, when working with a vacuum type furnace and employing temperatures of say 1200 C.,-1275 0., 1300 0., 1375 0., 14.50 0. and 1700 0.. I have obtained the following results: (1) 11- that the iron oxid is reduced'ahead of the manganese oxid; (2)- that the manganese reduction begins as low as 1200 C. and probbly lower, and is fairly r id t 13000 (3) that in a vacuum furnace, above 1300 '11 C.,- the loss of manganese is excessive, al-

though in a blast furnace such as employed in practice, the commercial lossesdo not approach those found in the vacuum furnace, owing among other thin to the re of the temperatures; (4 that the silicon is reduced at 1700 C., and a little below, while of course other small percentages of silicon are reduced below 1500 C. In other words, in a vacuum furnace, itvis perfectly .prac- 125 ticable to prepare ferro-manganese at from say 1300 C. to'1350 0., for at such temperature the metal will undoubtedly settle out, while if the temperature is carried as .high as 1700 C., a sihco-speigel will result,

lation v Accordingly, it will be seen that among other things I have discovered that employing a furnace, and properly regulating its temperature so as not to permit the molten bath to rise above say 1500 (I, the upper portions of the charge will be ata suffieientl y low temperature to practically save all of the volatilized manganese and to bring it back to the molten iron.

It is well known that prior to my invention ferro-manganese makers counted on a loss of say 20% to 25% of manganese in the furnace due to volatilization. My process, on the other hand, not only avoids this loss, when a charge high in manganese is employed, but owing to the fact that this said loss is avoided I am enabled to work with a charge as low in manganese as that stated in the specification and to commercially produce a ferro-manganese alloy high in manganese from said last named charge, which result would not be possible by-the processes heretofore employed.

It is obvious that those skilled in the art may vary the details of construction of the furnace, as well as the steps of the process without departing from the spirit of the invention, and therefore I do not wish to be limited to the above disclosure except as may be required by the claims.

What I claim is:

1. The process of making a ferro-mangafurnace; whereby the ascending manganese vapors are caused to condense on the cooler portions of sald charge, to be carried back to said ,zone and to alloy with the molten iron there present, substantially as described.

2. The process of making a ferro-manganese alloy which consists in providing a furnace charge containing the oXids of iron, manganese, and silicon, as well as lime stone and carbon; feeding said charge to the fusion zone of a furnace; and heating said charge to a temperature between 1300 C. and 1550 (1, While maintaining a reducing atmosphere in said furnace, substantially as described.

3. The process of making a ferro-manganese alloy which consists in providing a furnace charge containing the oXids of iron,

zinc, manganese and silicon, as well as limestone and carbon; feeding said charge by gravity to the fusion zone of a furnace; heating said charge to a temperature sufficient to fuse a portion of the same, and to volatilize a portion of the manganese, but insufficient to reduce the silicon oXid present, or to drive the manganese out of the. furnace, while maintaining a reducing atmosphere in said furnace, and removing the zinc vapors and evolved gases; whereby the ascending manganese vapors are caused to condense on the cooler portions of said charge, to be carried back to said zone and to'alloy with the molten iron there present, substantially as described.

4. The process of making a ferro-manganese alloy containing silicon which consists in providing a furnace charge containing the oxids of iron, zinc, manganese, silicon and carbon; feeding said charge to the fusion zone of a furnace; heating said charge to substantially 1500 C. while'maintaining a reducing atmosphere in said furnace, substantially as described.

In testimony whereof I affix my signature, in presence of two witnesses.

HARRY SCHAGRIN.

(I. G. WREN. 

